The Java Language Specification, Third Edition

5.1.4 Widening and Narrowing Primitive Conversions CONVERSIONS AND PROMOTIONS
84
0x0000 and 0xffff; it explains the char results, which also are the low 16 bits of
these values, namely, '\u0000' and '\uffff'; and it explains the byte results,
which are the low 8 bits of these values, namely, 0x00 and 0xff.
Despite the fact that overflow, underflow, or other loss of information may
occur, narrowing conversions among primitive types never result in a run-time
exception (§11).
Here is a small test program that demonstrates a number of narrowing conversions
that lose information:
class Test {
public static void main(String[] args) {
// A narrowing of int to short loses high bits:
System.out.println("(short)0x12345678==0x" +
Integer.toHexString((short)0x12345678));
// A int value not fitting in byte changes sign and magnitude:
System.out.println("(byte)255==" + (byte)255);
// A float value too big to fit gives largest int value:
System.out.println("(int)1e20f==" + (int)1e20f);
// A NaN converted to int yields zero:
System.out.println("(int)NaN==" + (int)Float.NaN);
// A double value too large for float yields infinity:
System.out.println("(float)-1e100==" + (float)-1e100);
// A double value too small for float underflows to zero:
System.out.println("(float)1e-50==" + (float)1e-50);
}
}
This test program produces the following output:
(short)0x12345678==0x5678
(byte)255==-1
(int)1e20f==2147483647
(int)NaN==0
(float)-1e100==-Infinity
(float)1e-50==0.0
DRAFT
5.1.4 Widening and Narrowing Primitive Conversions
The following conversion combines both widening and narrowing primitive convesions: